1,721,097 research outputs found
Free-electron-driven nanoscale light sources: from Hertzian antennas to metamaterials
No full textThis thesis reports on the development of new types of nanoscale optical light sources driven by free-electrons and on the investigation of the underpinning physical phenomena. It is focused on three types of nanoscale light sources with increasing degree of complexity: a nanoscale antenna, an undulator-based tuneable nanoscale light source and a metamaterial-based spatially coherent light source. I have demonstrated for the first time that a nanoscale Hertzian antenna can be driven by free-electrons. The studied nano-antennas consisting of pair of gold nano-rods spaced by a gap resemble conventional radio dipole antennas. Nanoantennas, driven by electron beam produce emission in the visible part of the spectrum. I show that these nanoantennas are most efficiently fed in the region of closest proximity between their two elements, in particular, where the light density of states reaches a maximum. I have developed for the first time a tuneable nanoscale light source driven by free-electrons, the light-well. Alike a free-electron laser that exploits magnet-based undulators, the light-well is based on a nanoscale undulator, a cylindrical channel through alternating metal-dielectric nano-layers. A fast electron propagating through the channel emit light at the wavelength linked to the electron energy and the period of the undulator, thus allowing for a continuous tuning of the output radiation. It has been achieved a 200 nm tunability range in the vis-NIR range at wavelengths between 750 and 950 nm with light at the level of 200W/cm2. Furthermore, I have performed a comprehensive numerical analysis of the light-well by modeling a free electron propagating in the undulator which has lead to a deeper understanding of its physical mechanisms. I demonstrate for the first time an electron-beam driven metamaterial light source that converts the kinetic energy of tree-electrons into spatially coherent optical radiation. It is based on a fundamentally new radiation phenomenon: the injection of free electrons into the metamaterial leads to a directed light emission that comes from synchronized plasmonic oscillations of the ensemble of metamolecules, the individual building blocks of the nanostructure. The effect results from the synchronizing interactions between the metamolecules leading to the spectrum narrowing with the increasing number of metamolecules involved. Depending on the type of metamaterial used I observed emission of narrow-divergent radiation in the visible range from 640 to 760 nm. These results - in principle - demonstrate an alternative to the laser, a threshold-free way of generating spatially coherent and spectrally narrow electromagnetic radiation
Introduzione
No full textL'introduzione presenta gli obiettivi di questa raccolta, la figura dello studioso i cui scritti rendono omaggio e descrive l'impostazione metodologica e i diversi. temi affrontati nel vlum
Related data for: Optical Rashba effect in a monolithic light-emitting perovskite metasurface
No full textData for: Optical Rashba effect in a light-emitting perovskite metasurfac
Related data for: Metamaterial enhancement of metal-halide perovskite luminescence
No full textData for figures v1.xlsx contains experimental and simulated data; .mph files are COMSOL files that allow to replicate the simuations
Related Data for: Enhancing cooperativity of molecular J-aggregates by resonantly coupled dielectric metasurfaces
No full textExperimental and numerical data for the paper "Enhancing cooperativity of molecular J-aggregates by resonantly coupled dielectric metasurfaces
Related Data for: Phase-change perovskite metasurfaces for dynamic color tuning
No full textData for: Phase-change perovskite metasurfaces for dynamic color tunin
Related data for: Topological Insulator Metamaterial with Giant Circular Photogalvanic Effect
No full textData for the paper: Topological Insulator Metamaterial with Giant Circular Photogalvanic Effec
Manipulation of single photon quantum states by coherent perfect absorption in a fiber network
No full textRelated data for: Perovskite metasurfaces with large superstructural chirality
No full textData for: Perovskite metasurfaces with large superstructural chiralit
- …
